Field of the Invention
The present invention relates to an image forming apparatus including a conveying path where a paper sheet is reversed.
Description of the Related Art
An electrophotographic image forming apparatus includes a function of performing duplex printing after reversing a paper sheet and a function of ejecting a paper sheet with the paper sheet reversed. Recently, printing on a long paper sheet of a size that is more than a regular size such as an A4 size is increasingly demanded of such an image forming apparatus.
A reverse conveying path is a structure for switching a conveying course of the paper sheet by reversing a conveying direction of the paper sheet. A proposed technique provides the reverse conveying path below a paper cassette (refer to, for example, JP 11-208962 A).
The reverse conveying path needs to have a length that is not less than a length of the paper sheet along the conveying direction. Accordingly, to form the reverse conveying path having the length adapted to the long paper sheet inside the image forming apparatus, a proposed technique connects a vertically extending conveying path that is provided side by side with a plurality of vertically aligned paper cassettes and a horizontally extending conveying path that is provided below the lowermost paper cassette.
In the image forming apparatus including the reverse conveying path, when the paper sheet remains jammed in a conveying path where the paper sheet cannot be removed, a proposed technique conveys this paper sheet to a position where the paper sheet can be removed (refer to, for example, JP 2005-338506 A).
To facilitate the removal of the paper sheet from the reverse conveying path, a proposed technique forms a space for the paper sheet removal on a predetermined side of the reverse conveying path (refer to, for example, JP 03-073769A).
The image forming apparatus is provided with, at a part of the conveying path, a structure capable of releasing pressure of a pair of rollers on the paper sheet remaining jammed in the conveying path, thereby facilitating the paper sheet removal.
Moreover, the structure for releasing the pressure of the pair of rollers on the paper sheet is included in a structure for performing paper positional correction that is called registration rocking, so that friction is reduced when the paper sheet is moved in its width direction orthogonal to the conveying direction.
In the reverse conveying path provided side by side with the paper cassettes, a guide plate for guiding the paper sheet during conveyance can structurally be opened and closed by hand for facilitating the removal of the jammed paper sheet, and the pressure of the pair of rollers on the paper sheet can structurally be released in synchronization with the opening of the guide plate.
To remove the paper sheet that is conveyed into the reverse conveying path for duplex printing, for example or the paper sheet that is conveyed into the reverse conveying path where the paper sheet can be removed after remaining jammed in the conveying path where the paper sheet cannot be removed, operation for opening the guide plate is performed.
When the guide plate of the reverse conveying path is opened for removal of the long paper sheet that is conveyed into the reverse conveying path, the long paper sheet remains astride the reverse conveying path provided side by side with the paper cassettes and the reverse conveying path provided below the paper cassettes. Visual identification of the long paper sheet is thus facilitated, and because the pressure of the pair of rollers is also released, the long paper sheet can be removed with ease.
However, when the guide plate of the reverse conveying path is opened for the removal of the long paper sheet with a paper sheet of the regular size conveyed into the reverse conveying path, the pressure of the pair of rollers is released, so that the paper sheet remaining in the reverse conveying path provided side by side with the paper cassettes moves under its own weight into the reverse conveying path provided below the paper cassettes.
The reverse conveying path below the paper cassettes is provided in a narrow space, so that the paper sheet conveyed into this reverse conveying path provided below the paper cassettes is visually hard to identify. The reverse conveying path below the paper cassettes is not provided with, for example, a structure for opening and closing a guide plate, thereby requiring the paper sheet to be pulled out in the conveying direction for removal, which is not easy. To increase the space below the paper cassettes, the apparatus needs to be increased in size. Providing the structure for opening and closing the guide plate also to the reverse conveying path provided below the paper cassettes increases the size of the apparatus and structurally complicates the apparatus.